EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Heat treatment with an electric current has gained interest in the last few years. However, the physical phenomena occurring in these type of treatments are not always fully understood. Thus, to study the influence of the electric current on the interstitial diffusion of carbon, an ARMCO iron sample is placed between the two graphite punches of a Spark Plasma Sintering facility. The current between the punches is used to regulate the temperature of the sample. The sample is heated in the intercritical domain (between 727 °C and 912 °C). The diffusion of carbon in ferrite induces its transformation into austenite. After cooling, the microstructure of the sample gives information on the transformation fronts positions and C concentration profiles. The transformation front velocity is higher in the direction of the electric current and lower in the opposite direction. To understand and predict this phenomenon, a model accounting for the allotropic phase change and the influence of the electric current on carbon mass transfer in iron is proposed. The simulation results are compared with the experimental observations allowing the identification of some model parameters.